The present invention relates generally to packers used for isolating portions of a drill hole or the like and more particularly, to inflatable packers of the type having an expandable gland which may be inflated by a fluid to cause the gland to engage the surface of the surrounding hole in sealing relationship.
An inflatable packer of the type presently known in the art consists generally of an elongate, rigid, inner tubular member having packer head members mounted at either end. Packer head members are generally annular in shape having diameters substantially exceeding that of the inner tubular member. Opposite ends of a tubular gland member are generally sealed to the outer annular surfaces of the head members thereby enclosing the inner tubular member within the gland member and forming an annular cavity between opposed surfaces of the inner tubular member and gland member. The internal tubular member provides structural integrity to the packer and may also accommodate the flow of fluids or interior pipe or wire placement or the like. The annular cavity between the gland member and the inner tubular member may be inflated with air to cause the packer element to expand and engage the surface of a hole, pipe casing, or other surrounding surface in which it is enclosed.
Inflatable packers have been used in a variety of applications to bring about a supportive or sealing contact between the packer gland and a portion of an elongate hole while simultaneously providing means for access to various zones along the length of the hole through the packer inner tubular member. For example, inflatable packers have been used to support sealed sections of casing pipe or drill pipe or a tubing string within a borehole. Packers have also been used to support an inner tubing string within an existing outer tubing string. Inflatable packers have been used to isolate zones within a borehole for testing, pumping and sampling purposes and as an integral part of pneumatic sampling and pumping systems. Packers have also been used to plug off a portion of a hole or pipe or alternately, to seal off a leaking portion of a sewer or waterpipe while simultaneously providing a fluid passage therethrough by means of two packers, one positioned on either side of the leak, and conduit supported between the packers. Packers have also been used in numerous other applications well known in the art. Prior to the present invention, each different use generally required a different type of packer.
With prior art packers, the packer heads have been considerably larger in diameter than the inner tubular member in order to provide sufficient strength to couple the packer to other connecting elements while simultaneously providing an attachment surface for the gland member. The problem with such an arrangement lies in the fact that the overall dimensions of the packer at the point of connection of the gland member to the packer heads is considerably larger than the diameter of the inner tubular member. Thus, there is a great size differential between the diameter of the passage provided through the packer by the inner tubular member and the diameter of the surrounding hole. This size reduction in the packer passage, of course, limits the amount of test conduit, etc. which can be inserted through the inner passage or in case of pumping operations, greatly limits the fluid flow rate through the hole because of the restriction produced by the packer.
In existing packers testing cables, air lines, etc., are often passed through conduit positioned in peripheral bores in the head members and extending between the heads through the annular cavity created by the gland and the inner tubular member. The placement is necessitated because of the lack of space within the inner tubular member. As a result, most such packers can only be used for a single purpose because of their fixed conduit configurations.
The inflatable gland of the packer has caused problems because of its tendency to rupture at high pressures or when encountering sharp or uneven surfaces of the type often associated with boreholes through rocky layers. The use of reinforcing material has met with only partial success in the past due to the fact that the reinforcing material, if sufficiently strong to prevent rupture of the gland has proven to be too unyielding to provide adequate inflation in many circumstances.
Thus, a need exists for a packer having an inner passageway of a greater diameter with respect to the packer outer diameter for providing improved fluid flow capacity or instrument placement within the packer. Such a packer should be adaptable to multiple uses and easily converted from one use configuration to another without major structural modifications. It is also desirable to provide a packer having a reinforced gland member which is capable of being inflated to high pressures and used against uneven or rough surfaces without rupture while simultaneously providing sufficient expansion to cause proper sealing engagement with a surrounding hole.